Have a knocking noise in engine and white smoke coming out exhaust? Does this year accord have a timing belt ?

To my knowledge, all Hondas in the U.S. use timing belts.

The white smoke is indicative of a head gasket problem. Coolant is likely getting into your oil.

Don't wait too long to have this checked out. You could destroy your engine.

The white smoke is from a blown headgasket, your coolant is leaking into one or more cylinders and that's actually steam that you see coming from your tailpipe.
When this happens, your coolant level drops (because it's pumping it out the tailpipe), your car overheats, and of course it will knock as it overheats. An overheated car is sluggish, as well.
Another bad thing that occurs by driving a car with this problem is that the coolant is washing the oil off your cylinder walls and your rings will tear up your cylinder walls as they self-destruct.
Head gasket replacement is not an easy fix nor is it cheap, and usually you'll need to get the head machined to make it perfectly straight again - heads warp from overheating. A good mechanic can do a head gasket replacement in a few hours.
Overheating can cause knocking.Your best bet is to replace your motor because usually the knocking noise is caused by a spun bearing which would cost a lot to repair.